Hussein’s family said in a statement on Tuesday that a new investigation has been opened against the journalist, who has already spent more than 880 days behind bars without charge.
An Egyptian court on Thursday had upheld a May 21 decision to release Hussein under “precautionary measures” which would have restricted his movements, but freed him from jail.
The Qatar-based journalist was transferred from southern Cairo’s Tora prison to a holding cell in Giza on Saturday where he awaited final clearance from the National Security Agency’s office.
“After spending a night at the police station, the family was surprised to learn that Mahmoud had been taken to the office of the prosecutor for state security,” the statement read.
The family then waited on Sunday for Hussein to be released from the police station as they were told that the visit to the state security’s office was part of the release formalities.
However, “he was taken back to Tora prison,” the family statement said, and that no official reason was given for his continued detention.
The journalist has been in custody since 2016 without facing formal charges or a trial. He has not been convicted of anything.
Hussein, an Egyptian national who works for the Al Jazeera Arabic television channel based in Qatar, was arrested on arrival on December 20, 2016, while travelling to Egypt to visit his family.
Hussein was accused of “incitement against state institutions and broadcasting false news with the aim of spreading chaos,” allegations he and the Al Jazeera Media Network deny.
Gamal Eid, executive director of the Arabic Network for Human Rights Information, said under Egyptian law Hussein should have been freed within 24 hours of Thursday’s release order by the court.
“This is a final court ruling but the problem is that security forces delay releases when they do not like those freed,” Eid told Al Jazeera last week.
Hussein’s detention was in violation of both Egyptian and international laws, with the former setting 24 months as the maximum period for pre-trial detention.
Egyptian authorities have repeatedly renewed his two-year detention.
According to Hussein’s lawyer Taher Abul Nasr there are at least 20,000 people currently in detention without charge in Egypt for political reasons.
Hundreds of them have already exceeded the legal two-year pre-trial term, he said.
Since the overthrow of Egyptian President Mohamed Morsi in 2013, a senior member of the Muslim Brotherhood, Al Jazeera Media Network has been portrayed as Egypt’s national enemy for its coverage of the group.
That same year Egypt arrested and later imprisoned Al Jazeera’s Abdullah Elshamy, Baher Mohamed, Mohamed Fahmy and Peter Greste on charges of spreading “false news” – cases that were widely condemned by international media outlets and many politicians. All have since been freed.
A former editor-in-chief of Al Jazeera Arabic was sentenced to death in absentia for purportedly endangering national security.
Several other Al Jazeera journalists have also been charged in absentia of spreading lies and supporting “terrorists” – a reference to the outlawed Muslim Brotherhood organisation.
Since his coup removed Morsi, President Abdel Fattah el-Sisi has waged an unprecedented crackdown on dissent, arresting thousands and rolling back freedoms won after the 2011 uprising that ended decades of rule by Hosni Mubarak.
In 2017, the Egyptian government blocked access to Al Jazeera’s news website along with dozens of others it deemed too critical of Sisi’s regime.
According to a 2018 report by the New York-based Committee to Protest Journalists, Egypt, along with Turkey and China, was responsible for more than half of journalists jailed around the world for the third year in a row.
Reporters Without Borders ranked Egypt 163rd out of 180 in its 2019 Press Freedom Index.